National Party President Peter Goodfellow has emailed party members saying a review into the party's disastrous election campaign found "the disunity, leaks and poor behaviour" were the key factors in that result.

The email was sent this morning, just after National Party MPs went into their weekly meeting to discuss the review, which the NZ Herald was told was so brutal that some believed even the MPs should not be shown it in full.

The email said party members would be invited to a series of meetings over the next weeks to see a summary of the review and the recommendations: but the full report seems unlikely to be shared widely.

It is expected that at least a summary of the review will be released publicly this week, but the full review is likely to be kept in-house.

Party leader Judith Collins would not talk about the review ahead of that meeting, saying only that the caucus would discuss it that day and that some of the findings were self-evident.

The Herald was told that it was so unstinting that some did not want the caucus to see it – both because of the risk that it would be leaked and undermine the party's attempts to rebuild as blame was apportioned.

There were also concerns about "natural justice" issues in the review, referring to people who may not be able to defend themselves publicly or to the caucus.

Another source said that nobody came out of it looking good, but it should be shown to party MPs or the lessons in it would not be learned.

In his email, Goodfellow described the review as "fulsome, detailed" and said it "contained concrete recommendations for improvement" and that the board accepted all of the recommendations in the review.

He said it found many contributing factors to the poor election result: "Chief among them the disunity, leaks and poor behaviour that severely impacted public perception of National as an alternative to the Labour Government.

"But this was by no means an isolated factor."

The email said rebuilding "a united, high functioning team must be out number one priority".

He said a summary of the results and the recommendations would be shared with party members in a series of regional meetings over the next few weeks, "in order to rebuild that trust and unity".

However, the review would not be published: "To do so would give our political opponents the much-needed distraction they want from us holding the Government to account for its failings."

The review was commissioned by the National Party board after the disastrous election result of 25.6 per cent, and the string of leadership changes from Simon Bridges to Todd Muller to Judith Collins in the five months before the election.

It was conducted by Mark Darrow, Judy Kirk, Kate Wilkinson, Jamie Beaton and June McCabe and was to look at that period in the party, the caucus and the campaign team.

Former National Party leader Sir John Key had also read the riot act to those in the party who had been leaking when Key spoke at the party's annual conference after the election, telling MPs to either stop leaking or quit Parliament.